rendering sooty bricks

[plasticpigeon]

Hello pppeople. I'm sure this has been asked before but I can't find anything quickly. I need to render some sooty bricks. I have scrubbed with water and detergent and got the loose stuff off. Some bricks show their original orange colour now, but many still have a hard but very thin black coating. I could probably get this off with a wire brush, but if I am going to render (cement as I am going to tile onto it) do I need to clean them thouroughly?

Thanks all.

 

[Zebra]

No, I don't reckon so. If you're going to use cement and tile over it then the colour won't show through, and if you've got the loose stuff off, then the render will stick.

 

[Zebra]

Had another thought. Is the black coating shiny? Some of mine have a thin shiny black coating on them, and I think that is not soot, but where the brick has been over-fired when it was made, and some of the sand in it has turned to glass. Forgive me if stating the obvious.

 

[plasticpigeon]

Hi Zebra

It is a shiny coating, but does come of with aggressive mechanical means such as a wire brush so I think it is just soot really well stuck on. I am going to wire brush the bricks to get as much off as possible but I won't bother getting them pristine. I'm not looking forward to cement/sand rendering the complex shapes in the fireplace but i think it will be the best surface to tile onto. The whole thing is a ridiculously tight fit and I should never have tried to attempt it, but I've started now, and there is nowhere else for the cooker to go unfortunately.